1. Field of the Invention
The present invention relates generally to power over Ethernet (PoE) and, more particularly, to a system and method for physical layer device enabled PoE processing.
2. Introduction
In a PoE application such as that described in the IEEE 802.3af (which has now part of the IEEE 802.3 revision and its amendments) and 802.3at specifications, a power sourcing equipment (PSE) can deliver power to a powered device (PD) over Ethernet cabling. Various types of PDs exist, including voice over IP (VoIP) phones, wireless LAN access points, Bluetooth access points, network cameras, computing devices, etc.
In accordance with IEEE 802.3af, a PSE can deliver up to 15.4 W of power to a single PD over two wire pairs. In accordance with IEEE 802.3at, on the other hand, a PSE may be able to deliver up to 30 W of power to a single PD over two wire pairs. Other proprietary solutions can potentially deliver higher or different levels of power to a PD. A PSE may also be configured to deliver power to a PD using four wire pairs.
In the PoE process, a valid device detection is first performed. This detection process identifies whether or not a PSE is connected to a valid PD to ensure that power is not applied to non-PoE capable devices. After a valid PD is discovered, the PSE can optionally perform a power classification. In a conventional 802.3af allocation, for example, each PD would initially be assigned a 15.4 W power classification after a Layer 1 discovery process is implemented.
After a valid PD is identified and possibly classified, power can be allocated to the port. In this allocation process, a determination can be made as to the amount of power that can be delivered to the PD relative to the amount of power available to the PSE. Typically, a PSE can distribute a fixed pool of power amongst a plurality of PDs that are each coupled to a network element such as a switch.
The allocation of power to a PD can be based on a power budget, which can identify the amount of power allocated to the port to which the PD is coupled. In one example, the power budget allocated to the port can also consider the power loss attributable to the cable. In one embodiment, the amount of power allocated to the port can be fixed or dynamic. In one example, dynamic budgeting of power to a PD can be based on current or anticipated changes in the power consumed by the PD.
Beyond the allocation of power budgets to the PD, further monitoring functions can be implemented to manage the PD. What is needed therefore is a mechanism that enables efficient control of the various PoE processes.